The flashbacks had come again, unwelcome and unexpected after dinner on a recent night when Steve Piotter was hoping to relax and watch a movie with his wife at their home in Healdsburg.

Piotter, 59, sat down on his couch and prepared for waves of anxiety to take over, the hallmark of the post-traumatic stress syndrome he's experienced since he retired from a 26-year military career in 2009. Then a Labrador-golden retriever mix named Major walked over, placing his head and then his entire upper body onto Piotter's lap.

"It absolutely comforted me and consoled me and got me through it," Piotter said. "If I didn't have Major, who knows what it might have escalated into. He settled me down."

Piotter and his wife, Judy, welcomed Major into their home last month after an intense two-week training program through Canine Companions for Independence, a Santa Rosa-based nonprofit that has provided skilled dogs to people with physical disabilities since 1975. Major has already become Piotter's constant sidekick.

The effectiveness of trained dogs for people suffering from PTSD is still not fully embraced by researchers and veterans groups. The U.S. Department of Veterans Affairs funds service dog programs for veterans with mobility issues but not psychological ones.

But veterans using dogs to help with their physical disabilities have reported psychological benefits, too. And about two years ago, the agency began funding a study to look at the benefits of service dogs provided to veterans suffering from chronic mental health issues.

Canine Companions provided 100 trained dogs for the research project, and a report on the findings is expected to be published next year.

Paige Mazzoni, Canine Companions' chief executive officer, said preliminary reports from the study have confirmed the psychological benefit the animals bring to veterans with physical injuries her organization has observed for years.

"You can see that part of the value they're getting with their dogs is that it's helping with the nonphysical issues as well," Mazzoni said.

In a pilot program begun last month, the group provided dogs to four veterans including Piotter. They will connect another group of veterans with skilled dogs in December.

Piotter enlisted in the U.S. Army in 1983 and served in the military police for seven years. Then he joined the National Guard, and his unit took part in many actions abroad, including the Panama invasion in late 1989 and early 1990 and the 1991 campaign in Kuwait.

He's proud of his service but "when they say war is hell, that's exactly what they mean," Piotter said.

What was once called "shell shock" or "combat fatigue" is now better understood as a form of anxiety common among combat veterans that can involve reliving a traumatic experience or event, or feeling distant or angry.

The symptoms don't dissipate with time and often get worse. People can experience hyper-vigilance, paranoia, emotional numbing, nightmares, flashbacks and hallucinations, according to the American Psychiatric Association.

At Canine Companions, dogs are trained to respond to verbal commands and to come close when its handler feels anxious or create space around a person when feeling cramped in public.

Retired Marine Cpl. Matt Raible trains with Jason, his third service dog through Canine Companions for Independence Inc., a non-profit that trains and provides service dogs. Matt and Jason passed the program together in November. Besides his physical disabilities, Raible says the dogs have helped him with post-traumatic stress. Canine Companions is now working with the VA in a new comprehensive study to determine if the dogs benefit veterans with PTSD, the first study of its kind.COURTESY OF CANINE COMPANIONS FOR INDEPENDENCE INC.